Your speaker baffles look nice, but appearance is only half of the game. There is actually quite a lot of science behind speaker box design. To get the most from your speakers, you need a box that's tuned (acoustically) to the frequency range that you want the speakers to produce. The speaker box design can make the difference between speakers that just make noise, and ones that sound great.
First of all, in order for a speaker box to work properly, it needs to be a complete box (and on large boxes, the walls need to be reinforced, so they don't resonate). Second of all, the internal volume of the box needs to be a certain size, depending on the speaker, and what frequency range you want it to produce.
Ported boxes are typically used for woofers and subwoofers, to improve low-frequency performance. To do this, the port needs to be a certain diameter, and a certain length. Otherwise, the port is pretty much useless.
I realize it may seem like I'm being too critical. But I'm not trying to be rude. We've all been in the same situation, at some time or another. An online search for speaker box building should turn up lots of information. But here is a good place to start: http://www.diysubwoofers.org/
And last but not least, the Fiero interior seems to lend itself to sealed woofer boxes. A ported box may end up sounding too "boomy", because the Fiero interior amplifies some of the low-frequency sound. Plus, there isn't a lot of room inside a Fiero. So getting a properly sized ported box (which are usually larger than sealed boxes) in there might be a challenge.